This invention relates generally to rotary die cylinders used in the printing industry for slitting, scoring, perforating or line hole punching operations and particularly to a cylinder assembly having an improved means of attaching and securing hardened bearers to the mating die cylinder bodies and the replacement of such bearers.
There are numerous conventional methods of attaching bearers to their mating cylinder bodies. For example, the bearers can be shrink fitted to the cylinder journal shafts or they can be welded. These methods have the disadvantage that excessive heat used in the processes tends to distort the metal parts. It is also known to provide the bearer and cylinder in a one piece construction. However, this tends to be expensive and does not permit replacement of the bearers alone. Another method of attachment, and perhaps the most conventional, is to provide the bearers with retaining screws. This has the disadvantage of requiring a keyway and is not a particularly accurate method.
Although there are patents which address the problem of attaching bearers, or similar parts, to shafts none of them adequately address the twofold problem of secure attachment and simple replacement. For example, known improvements include U.S. Pat. No. 2,613,571 (Herman) which discloses a shaft having a threaded portion receiving compatiblly threaded lock nuts for holding a set of spacers and slitters in place, the spacers and slitters being held against relative rotation by several connecting pins. U.S. Pat. No. 2,151,831 (Buccicone) discloses an intermediate shaft attachment having a threaded and tapered inner portion received on the shaft, a cooperating tapered outer ring and a threaded outer nut which bears against the ring to hold the intermediate attachment in place. Another approach is disclosed in U.S. Pat. No. 1,556,055 (Weber) and U.S Pat. No. 3,908,499 (Reed) which disclose saw and knife mounts respectively, provided by a flanged collar and a cooperating ring member, the flange being provided with pins received by the cutting member to prevent relative rotation. These improved devices tend to be complicated and therefor expensive.
The present invention avoids the above disadvantages in a manner not revealed by the known prior art.